Species identification and morphological differences of anguillid glass eels recruiting to Viti Levu Island of Fiji in the western South Pacific

There are six species of anguillid eels that live in various regions of the western South Pacific but the species compositions of glass eels recruiting to many of the islands of the region are not well known. A total of 1368 anguillid glass eels were collected fortnightly at the mouth of a small river at Namelimeli near Navua in Fiji Islands between April 2015 and June 2016. These were found through DNA barcoding to have a species composition comprising of two longfin eels Anguilla marmorata and A. megastoma, and one shortfin eel A. obscura. 35 glass eels from each species were then selected for morphological studies, it was found that the external morphological characters of anodorsal length ratios, caudal pigmentation patterns, and the internal characters of total, predorsal, and anodorsal vertebral counts were sufficient to classify these three species using morphological characters alone. These findings will simplify research and monitoring techniques of anguillid glass eel recruitment for conservation, fisheries management or aquaculture purposes in the South Pacific

Early life history of tropical freshwater eels (Anguilla spp.)recruiting to Viti Levu, Fiji Islands, in the western South Pacific

The oceanic early life histories of three species of tropical anguillid glass eels, namely Anguilla marmorata, Anguilla megastoma and Anguilla obscura, recruiting to Viti Levu, Fiji Islands, in the western South Pacific, were studied using otolith microstructures of 94 individuals. A. megastoma had the shortest leptocephalus duration, age at recruitment and metamorphosis stage (mean ± s.d. 104.7 ± 7.2, 141.3 ± 8.7 and 36.6 ± 8.5 days respectively), followed by A. marmorata (September–October recruitment peak: 113.0 ± 11.9, 115.1 ± 8.3 and 39.2 ± 11.1 days respectively; April recruitment peak: 152.2 ± 13.5, 154.0 ± 12.5 and 38.9 ± 10.1 days respectively) and A. obscura (118.0 ± 10.2, 168.4 ± 16.5 and 49.6 ± 12.5 days respectively). A. obscura also had the shortest oceanic glass eel duration of (12.2 ± 3.4 days), followed by both peaks of A. marmorata (23.3 ± 3.2 and 20.2 ± 3.3 days) and A. megastoma (20.7 ± 6.7 days). Otolith increment rates during the leptocephalus stage did not differ significantly among the three species, but there were significant differences between the leptocephalus duration and metamorphosis stage of A. megastoma compared with A. marmorata and A. obscura, as well as in the oceanic glass eel duration of A. obscura compared with A. marmorata and A. megastoma. There were also significant differences in the age at recruitment among all three species. Back-calculated hatch dates suggest separate peak seasonal spawning periods for each of the three species